Preheat the oven to 350°F. Grease a loaf pan.
Mix together the flax and warm water in a small cup and set aside.
Peel and chop the apples. In a large mixing bowl, stir together the oil, sugar, vanilla, greek yogurt, and milk. Once they're all stirred together, mix in the flaxseed mixture.
Next mix the baking soda, cinanmon, nutmeg, and salt.
Finally, with a spatula, fold in the wheat flour. Don't over mix or the bread gets tough. Once the flour is well incorporated, fold in the chopped apples. Leave about 2 tbsp out for topping the bread.
Pour the batter (or doughish batter) into the greased loaf pan and spread evenly. Sprinkle the remaining apples over the top.
Mix together the cinnamon sugar ingredients and pour this over the top of the bread. Lightly press it all down so it bakes into the bread.
Bake for about 55 minutes (you can check starting at 50, but you need to make sure a toothpick or a fork comes out clean when its poked. You also want to make sure the top doesn't sink down, even if the toothpick comes out clean but the center sinks, you will need to continue to bake for around another 10 minutes or so. If it sinks, the top middle of the loaf will be soggy.
Remove from the heat, allow to cool, slice and enjoy!